Overwriting and adding Built-in Functions and Tags

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Overwriting and Adding Built-in Functions and Tags

Overwrite or add built-in functions/tags with custom implementations - useful for backporting fixes or emulating different version behavior.

Overwriting/Adding Functions

Let's consider an example with the val function. The behavior of val was updated in Lucee 6.1 to more closely align with Adobe ColdFusion (ACF). To replicate this updated behavior in versions prior to 6.1, follow these steps:

Create a file at …/lucee-server/context/library/function/val.cfm with the following content:

<cfscript>
  public numeric function val(required obj) {
    if (!structKeyExists(server, "functionVal")) {
      lock name="functionVal" {
        if (!structKeyExists(server, "functionVal")) {
          server.functionVal = createObject("java", "lucee.runtime.functions.string.Val");
        }
      }
    }
    try {
      return server.functionVal.call(getPageContext(), obj);
    } catch (e) {
      return 0;
    }
  }
</cfscript>

After creating this file, restart Lucee. This custom implementation of the val function will now be used throughout your code. In this example, the original val function is called, but any exceptions are caught, and 0 is returned if an exception occurs.

This approach not only allows you to overwrite existing functions but also to add entirely new functions that will behave like built-in functions. You can find many built-in function templates in the …/lucee-server/context/library/function/ directory.

Overwriting/Adding Tags

The process for tags is similar. To create or overwrite a tag, use the …/lucee-server/context/library/tags directory. Custom tags need to follow the same interface as regular custom tags. You can refer to existing built-in tags in this directory as templates for your implementations.

By following these steps, you can extend or modify Lucee's capabilities to suit your specific needs.

See also